<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>promise的all方法</title>
</head>
<body>
    
</body>
<script>
    //promise.all()将多个promise实例包装成一个新的promise实例
    //只有当所有的promise实例的状态都为fulfilled最终结果才能执行.then
    //只要有一个promise实例的状态为rejected最终结果就会执行.catch

    let promise1 = new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve(1000)
        },1000)
    })

        let promise2 = new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve(1000)
        },1000)
    })

        let promise3 = new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve(1000)
        },1000)
    })

    let promise4 = Promise.all([promise1,promise2,promise3])
    .then((res) => {
        console.log(res);
    })
    .catch((err) => {
        console.log(err)
    })


</script>
</html>